Supporting surface for flying machines, parachutes, and the like, rudder surfaces and protecting surfaces



' Jan. 4 1927.

SUPPORTING SURFACE F LIKE! 'RUDDER UUDUDUUU UUUDDUUU UUDUUUU DDUUUUDU DUDUUUUD `DUUUDUDU DUUUUUD UDUUUDUD UDUUUUUU UDUDUDDD 1,613,348 E.FALKENTHAL on FLYING MAGHINES,.PARACHUTES, AND THE SURFAGES AND PROTEGTING SURFACES Filed Sept. 2; 1924 Patented JaIL, 1927.

lianwrn FALKENTHAL; or BERLIN-naamw, nmrm.

SUPEORTING ,RUDDER SURFACES 'AND Applicationled September 2, 1924, Serial No.

This invention relates to a special construction of the supporting planes for aeroplanes, kites, parachutes or the like.

According to the invention the supporting plane consists of a smooth supporting surface with permanently open small, closely arranged pertorations, these perforations i.

having smooth sharp edges and a distance between 'each other about equal with the smallest diameter ot a perforation, measured in the direction ot this diameter. 5

By this structure various advantageous results are obtained. lin the iirst place, the` weight ot'the supporting plane` is diminished,without at the same time diminishing the" supporting ability. ,'lhus neither the litt-ing power and steering ability of an aeroplane nor its resistance to the air in gliding is diminished. Moreover, the air friction on the plane surface is diminished by the perforations, as about haltI of the plane is composed of air. r

For parachutes a slower fall is ensured by the reduction of weight.

, The invention is based upon the observation that a smooth plate made as above described with :punched pertorations of the` aforesaid character otlers the same resistance to flowing air as an unperiforated plate. This result may -be explained bythe tact,` proven by experiment, that the impinging air stream is dispersed before and behind the plate into "a large number of separate eddies,V which completely dissipatethe air stream; while at a short distance behind the plate, viz, beyond the eddy-zone, no air flow occurs that can be regarded as originatingfrom the impinging air stream. The wholel energy of the air stream is therefore transmitted to the perforated surface, and the latter behaves practically as a closed or continuous surface. l It has further been ascertained that under some circumstances such a perforated surface has even more resistance to air or lifting power than a closed surface. This phe- -nomenon is perceived when the solid sur-g face elements or parts are of small absolute size or breadth, for` example about 10 millimetres. The increase of the pressure effect results from the fact that on the rear side of each small solid surface element between the perforations a suction effect occurs, and these numerous small-suction etfectsaddup to a considerable collectlve eiect, which supsUnrAcE ron FLYING MACHINES, PAnAcHUTns, Anuman LIKE,

PROTECTING SURFACES.

735,473, and .in Germany February 24, 1922.

plement the direct Windpressure. In the eir-l periments such a plate must have greater weight for resisting the air stream, and when used as a supporting plane it can carry ,more weight than when the perforations are ot' greater diameter.

For the etiicacy of lthe a eddies it seems desirable to take care that-on the rear side or theupper side ofthe supporting plane there shall be no longitudinal wind. This wind may be obviated by giving the iront or leading edge ot the supporting plane or wing a rounded form, such form having already .been found to be advantageous in the case of the closedfor'continuous surface supporting planes of aeroplanes. rllhe form oit the leading edge ,must be selected in such a way that it deflects then air stream impinging from the iront somewhat upwards, so that on the, upper side oi' the support-ing plane there will be a space in which the eddies can form undisturbed.

,'lhe perforations in the wing are limited to that part ot the wing whichdoes not form part4 oft' the rounded leading rim of the wheel.y .r

In the drawingv "ligure'l illustrates an aeroplane without such detailsl that are oil no interest for this invention. Fig. 2 illustrates'in cross section a wing consisting of one curved plane, and

Fig. 3 illustrates `a hollow win composed of two curved planes with a roun ed leading edge. 'i

'lhe supporting planes a (if the aeroplane Fig. 1n are provided with s it-like perforations Ab. of the kind described above., l'llhe slits are arranged in spaced rows arranged in parallel, the slits in each row being also arranged parallel to those of another row., and have a distance apart equalto the width of a slit.` f

cross-section, whichshape is known per se, and which consists of two curved'plane's a, a

united by a rounded leading edge/c, both' the planes a and a so aras they lie behind theleading edge being providedwitgiperforations I) according to the inventionffrAlter# natively, however, only the under plane a may be provided with perforations, 'the upbove-mentioned Figure 3 showsa hollow wing'of drop-likev I per plane a bein left solid and continuous. y

- The material or the supporting plane or wing may be of any desiredkindf. v

In the case of the hollow wing according to Figure 3 it may be made, for example, of

lSheet aluminium, which is provided with 2.5 to 3 centin'ietres Wide and being arranged f at similar distances from one another.

The supporting plane may however be made by weaving, for example in such a way that staggered interwoven square surfaces join one another at the edges, or that interwoven strips are` connected with one another only by the warp threads, and so forth. InF the latterV cases the breadth of the solid'surfaces and the distance between them may be substantially decreased. -The rou s of. thread that are not interwoven are in tlts case, in comparison with the'interwoven surfaces, to be regarded essentially as open perforations, as no perceptible air resistance occurs on the individual round threads.

`It is, of course, to be understood that the surface of the plane is smooth, i. e. free .of projections, such as hoods, cowls or other devices projecting either, above or below the plane or wing, such as have been proposed withl respect to large openings through the planes.

' The openings according to my invention are small `and numerous; they have sharp edges such as are formed in punching meta f1. In an aeroplane or the like, a smooth through, said perforations being substantially. perpendicular to the lwing and having s1nooth,"sharp edges and having a distance between them` about equal tofthe smallest diameter of a perforation measured in the direction of this diameter.

' 2. In an aeroplane or the like, a smooth wingfhaving a continuous surface witlrpermanently `open, closely arranged small perforations therethrough, these perforations having smooth, sharp edges and the dist-ance between them bein 'about equal with the smallest diameter ov a perforation measured in the direction of this diameter.

` 3. A supporting plane for aeroplanes or the like, having permanently open, closely arranged, narrow slits therein arranged parallel to one another and having smooth sha-rp edges, the distance between each two slits4 being about equal to the width of a slit, and the parallel rows of slits being spalced by unperforated portions of materia 4. A supporting plane for aeroplanes consisting of a wing of uniform surfaced material with permanently open, vclosely arranged, small perforations therethrough,

these perforations having smooth, sharp edges with the Adistance between them about equal to the smallest diameter of a perforation, the leading edge of the wing being bent over and free from perforations.

5. A supporting plane for aeroplanes, consisting of a hollow wing of solid material with drop-shaped cross-section, the under wing plane having small, permanently open, closely arranged perforations with smootn sharp edges, the distance between each two of said perforations being about equal with the smallest diameter of a perforation measured in the direction of this diameter.

6. A supporting plane for aeroplanes, consisting of a hollow wing of drop-shaped cross-section, both the upper and the under plane of the wing being provided with closely arranged small perforations right up to the fore, rounded edge of the wing, the said perforations having smooth, sharp edges and the distance between said perforations being about equal with the smallest diameter of' a perforation.

7. An aeroplane wing having a covering present-ing a smooth, generally uniform 'surface and having numeroussmall, closely arranged, sharp-edged open perforations extending through the covering, promoting the lane. l

tanceapart of the slots in a row not exceeding the width f the slots, and the distance apart of the rows of slots not exvcceding the length of the slots.

formation oi. eddies Ynear the surface of .the SIA supporting plane for aeroplanes or'v In testimony whereof I have signed my name to this specification.

ERWIN FALKENTHAL. 

